Before retiring, I "commuted" monthly on Acela Express between Washington & Boston. The worst part of the trip was over Metro North between New Rochelle and New Haven, where we'd often crawl among the commuter trains. If this project were to go forward, special care would have to be taken so that the Amtrak service between Penn Station & New Rochelle did not also go down the tubes. Except for the Hell Gate Bridge (which is now only 3 tracks vice the 4 it used to be) and a few other bridges, the right-of-way might be wide enough to accommodate additional tracks dedicated to commuter service.
Melgar is also correct in referring to the need for more trans-Hudson tunnels. One track in each direction is not adequate for safety and reliability. Nearest other crossing is many miles north, so there are no alternatives, save for car ferrying passenger trains across the Hudson, which is not feasible.
